Research

• Cryptology and Information Security: presently my main field of interest, in particular RSA cryptanalysis, applications of hash collisions, relations to number theory, identity management, traitor tracing, lattice based cryptology.
• Number theory: my original field of interest, in particular computational number theory, Diophantine equations, the abc-conjecture and the 3n+1-conjecture.

bibliography

project involvement

• CREST - Collusion RESistant Tracing
• MobiMan - Identity Management on Mobile Devices
• SLaBaC - Security of Lattice Based Cryptosystems

talks

• January 12, 2012: "Hard Lattice Problems", Indo-US Workshop "Mathematical and Statistical Aspects of Cryptography", Indian Statistical Institute, Kolkata, India.

• March 23, 2011: "De uitdaging van informatiebeveiliging", Studium Generale, TU Eindhoven.

• September 4, 2010: "Hoe je het cryptosysteem RSA soms kunt kraken", Vakantiecursus, TU Eindhoven.
• August 28, 2010: "Hoe je het cryptosysteem RSA soms kunt kraken", Vakantiecursus, CWI Amsterdam.

• November 25, 2009: "MD5 Considered Harmful Today", Securiosity, Nationaal Informatica Congres, Nijmegen.
• September 14, 2009: "The rogue CA attack - On the insecurity of MD5", Ecrypt II Workshop, Leuven.
• May 14, 2009: (met Marc Stevens): "Botsingen voor hashfuncties en de veiligheid van certificaten", Getronics, Zoetermeer.
• May 13, 2009: "Botsingen voor hashfuncties en de veiligheid van certificaten", GridForum Bedrijvendag, Amersfoort.
• April 24, 2009: "MD5 Considered Harmful Today", EiPSI First Anniversary, Eindhoven.
• April 6, 2009: "Alles onder controle op het Internet?", Veersymposium, Eindhoven.
• February 12, 2009: "Hashbotsingen - de stand van zaken", GovCert, Den Haag.
• February 6, 2009: "Voorspellen met een PlayStation3", Nederlandse Wiskunde Dagen, Noordwijkerhout.
• February 5, 2009: "Botsingen voor hashfuncties en de veiligheid van certificaten - de stand van zaken", GBO Overheid, Den Haag.
• January 7, 2009: "MD5 Considered Harmful Today", EiPSI Seminar, Eindhoven.

• December 12, 2008: "Hashfuncties: een wiskundige knoeiboel", TIASNimbas MSIT/MISM Diplomauitreiking, Eindhoven.
• May 20, 2008: "Hash-botsingen, de stand van zaken", NL-DEX 10, Digital Experts Exchange KLPD, Driebergen.

• March 15, 2007: "Hash collisions: an update", LogicaCMG SIG Security, Eindhoven.
• January 25, 2007: "Inleiding Cryptologie", dotNed, Utrecht.

• November 3, 2006: "Hash Collisions: A Crisis in Cryptography?", ITW Symposium, Delft.
• September 14, 2006: "Hash Collisions: A Crisis in Cryptography?", GOVCERT.NL Symposium, Scheveningen.
• June 13, 2006: "Recent Developments in Cryptanalysis of Hash Functions", with Arjen Lenstra, I4 Forum, Antwerp

• July 8, 2005: "Applications of Hash Collisions to Public Keys", Macquarie University, Sydney.
• July 5, 2005: "On the possibility of constructing meaningful hash collisions for public keys",
• June 29, 2005: "Partial Key Exposure Attacks on RSA", Macquarie University, Sydney.
• May 31, 2005: "Hash functies onder vuur", LogicaCMG, Amstelveen
• April 8, 2005: "Applications of Hash Collisions", EIDMA Cryptography Working Group, Utrecht

• October 28, 2004: "Internet-beveiliging", Congres "IT met het oog op de toekomst", Apeldoorn-IT
• April 17, 2004: "Cycles for the 3n+1-problem", Dutch-Belgian Mathematical Conference, Tilburg University
• April 2, 2004: "Partial Key Exposure Attacks on RSA", EIDMA Cryptography Working Group, Utrecht

• April 9, 2003: "The ICZ-attack on OpenPGP", Combinatorial Theory Seminar, TU Eindhoven
• February 5, 2003: "Cycles for the 3n+1-problem", Combinatorial Theory Seminar, TU Eindhoven

• October 4, 2002: "Weak RSA Key Pairs", EIDMA Cryptography Working Group, Utrecht

organisational

• co-organizer of the 3TU.AMI Opening Symposium, April 15, 2010
• co-organizer of the Lorentz Center Workshop Hash functions in cryptology: theory and practice, Leiden, June 2-6, 2008
• I have been a work group leader in Ecrypt-Aztec, co-organizing a number of "research retreats".
• As of September 1, 2011, the job of mediator (vertrouwenspersoon) for the PhD students in the TU/e Department of Mathematics has been taken up by Jacques Resing.

awards

• Crypto 2009 Best Paper Award for the paper "Short chosen-prefix collisions for MD5 and the creation of a rogue CA certificate" by Marc Stevens, Alex Sotirov, Jacob Appelbaum, Arjen Lenstra, David Molnar, Dag Arne Osvik and me.
• The "Rogue CA-attack" made it to number 1 of the Top Ten Web Hacking Techniques of 2009.

Erdös number

h-index